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• flac : Fix channel order for mono files.

  28 juin 2014, par Erik de Castro Lopo

  flac : Fix channel order for mono files.
  * The default channel mask for mono files was 0x0001 (front left) but it
  
    makes more sense to use 0x0004 (front center) for such files.
  * Also FLAC will accept not only mono WAV files with 0x0001 mask, but also
  
    with 0x0002 (requested at https://sourceforge.net/p/flac/bugs/390/)
  
    and 0x0004 (e.g. SoX creates mono files with this mask).
  * The comment about channel support was updated.
  * The error message
  
       "Use —channel-map=none option to store channels in current order ; FLAC files
  
       must also be decoded with —channel-map=none to restore correct order."
  
    is misleading : FLAC never changes the order of channels.
  
    Decoding with this options also sets the channel mask of the resulting WAV
  
    file to 0. Without this option the mask is equal to the value of
  
    WAVEFORMATEXTENSIBLE_CHANNEL_MASK tag.
  Patch-from : lvqcl <lvqcl.mail@gmail.com>
  

  • [DH] src/flac/decode.c
  • [DH] src/flac/encode.c

• Generate MPEG-DASH segments when requested [closed]

  16 septembre 2024, par John Smith

  Up front disclaimer : this question is almost identical to the one here : Generate single MPEG-Dash segment with ffmpeg but it seems that ffmpeg has updated over time and now the answer provided by Coumeu is no longer accurate.

  


  Using ffmpeg, I am attempting to "lazily create" the segments needed for MPEG DASH playback. I have a static manifest (MPD) which includes SegmentTemplates for 1 video and 1 audio stream.

  


  Only when the endpoints provided in the SegmentTemplate for init or media segments is hit it will generate this segment. In other words, nothing is processed up front.

  


  I am creating the init segment using the following movflags :

  


  +frag_keyframe+faststart+skip_trailer 


  


  I am creating the media segment using the following movflags

  


  +frag_keyframe+default_base_moof+delay_moov+skip_trailer+dash+global_sidx


  


  and the following additional commands any segment type :

  


  -map_metadata -1 -copyts -start_at_zero -map 0:${streamIndex}


  


  This results in playable video with the correct duration, but it seems to be switching fragments quite fast. On average one fragment per second. When I omit the delay_moov flag, the video also starts glitching, like it's stepping over I-Frames.

  


  My observations when I look at the boxes :

  


  

  • earliest_presentation_time (sidx box) is 0 for all segments

  


  • base_media_decode_time (moof->traf->tfdt box) is 0 for all segments

  


  


  I'm looking for either the correct command line to create segments on the fly, or hacky ways to get it done right if ffmpeg doesn't provide it out of the box. Even information about what to look for would be helpful, because my knowledge about mp4 and MPEG-DASH is running out.

  


• Anomalie #3386 : Spip derrière Varnish : port non-standard dans l’URL ?

  17 février 2015, par jluc -

  quote : "Parfois l’hébergeur te met un varnish en front et ne te permet pas de le configurer. C’est pour ça que je ne suis pas pour le fait d’exiger un réglage spécifique côté Varnish." Tout à fait. C’est le cas notamment de Gandi Simple Hosting pour lequel l’hébergé ne peut aucunement paramétrer varnish.